The nation's response to the needs for energy self-sufficiency could increase the number of hazardous agents released into the environment daily. Efficient and economical systems are needed to predict susceptibility of humans to hazardous agents and to monitor human populations for adverse genetic effects that may be caused by unforeseen mutagens. Most likely these needs can be met by further development of DNA repair synthesis and by measurement of tissue specificities of responses to hazardous agents. The significance of DNA repair synthesis will be enhanced by correlations of the extent of DNA repair with measurements of cytogenetic aberrations, with mutagenesis of mammalian cells, and with carcinogenesis as measured by cell transformation.